‘The Body Book’, by Cameron Diaz

The 41-year-old actress penned the health and lifestyle guide because she wanted younger women to be able to get advice some people wouldn't be open enough to share.

She told the Mail on Sunday newspaper's You magazine: "I never imagined I could create a book, let alone one this big. Because I am not that person.

"I am an actor - I don't produce, I don't direct, I have a very short attention span and I have progressed my career by listening to my intuition. I would think, 'What shall I do next?' and pick something that gave me that gut reaction.

"But then two years ago I had this absolute moment when it came to me that I had to do this book because nobody else was going to do it. I had to find a way to share the knowledge that I have about my body at 41 - and I'd had at 21."

The 'Annie' star has been surprisingly blunt in the book, discussing many intimate and sometimes embarrassing issues, including her teenage acne.

She added: "I think that for a young person, having bad skin is a real issue because your face is the first thing people look at when they meet you.

"So I wrote the book for my 16-year-old self, who I look back on and think, 'Why didn't I know these things then?' " - Bang Showbiz